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Impact crater on Mars

Impact craters on themoon

Impact craters on the Moon

Meteor hitting atmosphere

Leonid meteor swarm

Meteor hitting South Greenland 1997

Meteor dust, 0.01 mm

Meteorite find in Sahara

Meteorite find in the Antarctic

Iron meteorite, 5 cm

Stone meteorite, 8 cm

Asteroid, 17 km

Asteroid surface, 700 m visible

Barringer Meteor Crater, Arizona. 1.2 km diameter. Age: 49000 BP

Ayers rock Australia

Wolfe Creek Crater, Australia. 0.9 km diameter. Age: 300,000 BP

Saskatchewan, Canada. 5 km diameter.

Chad, Africa. 10 km diameter.

Ries Crater, Germany. 45 km diameter.

Nördlinger Riis crater rim

Nördlinger Riis Tectite

Earth and Moon

Young planet Earth collides with large asteroid?

Asteroid hits Earth 65 mill yr BP

Recent asteroid impacts with the Earth Stony asteroids with a diameter less than about 100 metres generally do not reach the Earth's surface. These objects usually explode several kilometres above the surface (an "airburst"). This was probably the case with the "Tunguska" Siberian event in 1908. The kinetic energy involved is substantial - a typical impact by a 50m object releases about 10 megatons of TNT and that of a 100m object releases about 75 Mt (the actual kinetic energy depends on several factors such as speed and density and can vary by a factor of more than 10). These explosions are equivalent in energy to large thermonuclear explosions and they can cause devastation over thousands of square kilometres - in the case of Tunguska the area of destruction was about 2,000 sq km or a circle of radius 25km. Fortunately the region was sparsely populated and had little effect on humans.

"Tunguska" Siberian event in 1908

"Tunguska" Siberian event in 1908, trees destroyed within 2,000 km2 area.

Tree rings recording "Tunguska" Siberian event in 1908

Asteroid hits Earth 65 mill yr BP

Chicxulub Crater, Yucatán, Mexico

Stevns, Denmark

Kap Steward formation, Jameson Land

Alder (i år) eller dato Sted Merknad 2 milliarder Sør-Afrika Vredefort, det eldste kjente krateret på Jorden. Estimert diameter 140-300 km. 290 millioner Canada Clearwater Lakes, to kratere med diametre 32 og 22 km 250 millioner Australia Woodleigh, diameter 130 km, oppdaget april 2000. Eksplosjonen kan ha forårsaket utryddelsen på overgangen perm-trias da nesten alt livet på Jorden ble utryddet. 215 millioner Quebec, Canada 200 millioner Chad, Afrika Manicouagan, 150 km krater 143 millioner Australia Gosses Bluff, 22 km krater 100 millioner Canada Deep Bay, 13 km krater 65 millioner Yucatanhal vøya 38 millioner Canada Mistastin Lake, 28 km krater Kjede av flere store kratere fra en rekke nedslag. Hvert krater er større enn 10 km. Chicxulub, spor etter 170 km krater, masseutryddelse av bl.a. dinosaurene. 35 millioner USA Chesapeake Bay, 85 km krater 5 millioner Namibia, Afrika Roter Ramm, 3 km krater 3 millioner Tadsjikistan Kara-Kul, 50 km krater 2,15 millioner SØ Stillehav 1 million Ghana, Afrika Eltanin asteroidenedslag forårsaket tsunami. Asteroide > 1 km Bosumtwi, 10,5 km krater 300 000 Australia Wolfe Creek, 0,9 km krater

65 millioner Yucatanhal vøya 38 millioner Canada Mistastin Lake, 28 km krater Chicxulub, spor etter 170 km krater, masseutryddelse av bl.a. dinosaurene. 35 millioner USA Chesapeake Bay, 85 km krater 5 millioner Namibia, Afrika Roter Ramm, 3 km krater 3 millioner Tadsjikistan Kara-Kul, 50 km krater 2,15 millioner SØ Stillehav 1 million Ghana, Afrika Eltanin asteroidenedslag forårsaket tsunami. Asteroide > 1 km Bosumtwi, 10,5 km krater 300 000 Australia Wolfe Creek, 0,9 km krater 49 000 Arizona, USA 120 600 Saudi- Arabia År 1490 (ikke bekreftet) Kina 30. juni 1908 Sibir, Russland Barringer-krateret ("Store meteorkrater"), 1,2 km diameter Wabar-kraterne i Saudi-Arabia Omtrent 10 000 mennesker rapportert omkommet Tunguska, trolig steinlegeme med diameter 60 meter. Legemet eksploderte ca. 8 km over bakken og flatla over 2000 km 2 skog og startet branner. 10-20 megatonn. 1930 Brasil Tunguska-lignende eksplosjon i luften. Legemet var 10-50 meter i diameter og forårsaket betydelig skade på bakken. Ingen kratere funnet Februar 1947 Russland Sikhote-Alin. Ett hundre kratere over en halv meter i diameter, det største er 14 meter. Skyldtes jernlegeme som gikk i oppløsning i ca. 5 kilometers høyde. Juli 1994 Jupiter Fragmenter av kometen Shoemaker-Levy 9 kolliderte med Jupiter og forårsaket nedslagssoner på størrelse med Jorden.

For comparison, the average annual death toll from earthquakes is about 10,000 per year. That of commercial airliner crashes is about 700 per year!

Risk of direct impact for a given location Diameter Kinetic Energy Area Devastated Average. interval (years) (m) Mt TNT sq km Earth "City" 50 10 1900 100 yr 30 million yr 100 75 7200 1000 yr 70 million yr 200 600 29 000 5000 yr 90 million yr 500 10 000 70 000 40 000 yr 290 million yr Inhabited Region & Expected Death toll 900 yr 1 million 8000 yr 3 million 30 000 yr 14 million 180 000 yr 30 million 1 km 75 000 200 000 100 000 yr 260 million yr 290 000 yr 60 million 2 km 1 million MT - 1 million yr - 1 million yr 1.5 billion All* 90 yr 14 million yr 800 yr Morrison D. and Chapman C. 1995 "The Biospheric Hazard of Large Impact". Proceedings of Planetary Defense Workshop.

Estimate of death toll from various types of impact Asteroid Diameter (m) Area devastated (sq km) "Typical" Direct Fatalities Ratio of indirect/dire ct fatalities Total fatalities Annual chance for inhabited regions 1 in... Equivalent annual death toll 50 1900 200 000 4 1 million 900 1100 100 7200 650 000 4 3 million 8000 400 200 29 000 2 000 000 6 14 million 30 000 500 500 70 000 4 000 000 8 35 million 180 000 200 1 km 200 000 7 000 000 8 63 million 290 000 200 2 km - - - 1.5 billion 1 million 1500 All 800 3900

71% of planet surface is water

.what about Norway?

Gardnos impact crater. Diameter 12 km. Age 350 mill yr BP

Gardnos area shortly before impact

Gardnos area at impact

Gardnos area 10 minutes after impact

Gardnos area 2 years after impact

Gardnos area now

Mjølnir impact, 141 mill. BP, crater diameter: 40 km